I have the nifty-fifty and I am in love with the kinds of images it can produce, particularly when it comes to portraits. I really enjoy the lens, but I have one problem; it is a little bit too tight for me. So I've been looking for a wider prime with similar attributes and have found the 28mm f/1.8 (as well as the Sigma 30mm f/1.4).

My question: Other than the obvious (price, focal length), how does the 28mm f/1.8 compare to the plastic fantastic especially in IQ? I've read a few reviews but nobody seems to compare the two.

2 Answers
2

Any lens wider than 50mm is going to be a retrofocus design and will be softer in the corners than your 50 1.8

The 28 f/1.8 is one of the slightly newer non-L primes, being released in 1995 (the 50 f/1.8 optical design dates to 1987) and comes in a better body than the f/1.8 with an ultrasonic focus motor.

Performance wide open in the centre is comparable but the corners suffer from chromatic aberration and softness, which unfortunately don't go away when stopped down. If you intend to use the lens for portraits this isn't too big a deal as you're corners are likely to be out of focus. However if you also intend to take this lens out to shoot landscapes you're going to be disappointed.

The Sigma 30 f/1.4 is sharper in the centre at f/1.4 than either Canon lens at f/1.8. It is in fact really good in this regard considering the price. However like the Canon 28 f/1.8 the corners are soft even when stopped down. You're also buying a ticket to the Sigma frontfocus lottery with this lens.

I've owned both the 50 f/1.8 and 28 f/1.8 and I mostly concur with the statements above regarding those, particularly the chromatic aberration on the 28: it is bad, and not just in the corners. Furthermore, it's not easily correctable in post-processing. As such, I would not recommend it as a portrait lens (nor any wide-angle lens, except for group shots...B/W, maybe?). I was tempted to pick up the Sigma 30, but held out for a Canon 24 f/1.4 L II :-) No regrets, just a lighter wallet and much, much better images with less effort in post.
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djangodudeSep 5 '12 at 14:52

The Canon 28mm f/1.8 is going to give you many benefits over the Canon 50mm f/1.8 II. For example it has full time manual, USM, a large focusing ring, non-rotating front element, closer minimum focusing distance, aspherical elements, and solid construction.

If you are shooting at f/2.8 I would say get whichever focal length you desire and that is your ticket. If you shoot at f/1.8 then the 50mm will probably have better performance at the corners, and the 28mm will probably have better performance in the center, especially on an APS-C sensor.

Image quality compared to the Sigma 30mm f/1.4 is very similar on the Canon 28 f/1.8. So either of those could realistically be bought based on your specific needs.

In my opinion this is a gap in the Canon lens lineup. They really do not offer a lens in this range that is reasonably priced, still sharp in the corners, and offers f/2.0 or better. The new Canon 40mm f/2.8 pancake lens comes close but is not f/1.8 obviously.

Honestly getting a wide angle high quality wide aperture lens is quite expensive and typically requires a full frame camera and a 24L or 35L. Most people end up using longer focal lengths with wide apertures and something like the 10-22mm for wide angle on the APS-C cameras.